In 1990, the National Electrical Code (NEC) was revised to require that electrical wires and cables mounted within a wall structure must be at least one-and-one-quarter (1.25) inches behind the inner wall surface. This code provision is intended to reduce the likelihood that a nail, or other sharp implement, would damage the insulation and potentially cause an electrical fire. The NEC further requires that a cable is secured at the 1.25 inch offset within 12 inches of an electrical box or other fitting, and at intervals of not more than 4.5 feet along a run.
A number of devices have been developed to implement the NEC requirement for a 1.25 inch offset, as described in the following patents:
U.S. Pat. No. 5,067,677 to Miceli is for a Wire Harness. This device is for mounting on the face of a wall stud to hold a number of wires spaced between the surfaces of a wall. The device has one arm for mounting to a stud and a second arm for attaching wires. A series of clips are placed along the second arm for receiving and holding wires.
U.S. Pat. No. 5,141,185 to Rumbold et al. is for a Wiring Clip. This patent discloses a clip having an L-shaped portion to be secured to a stud and a strut and hinged arm remote from the L-shaped portion, the arm is adapted for being folded back and locked around several wires.
U.S. Pat. No. 5,587,555 to Rinderer is for a Conductor Holding Device. This conductor holder has a support member having two perpendicular arms, one arm for being affixed to a stud and the other arm being formed with one or more holes. A clamp having a leg and a head is mounted with the leg through the one hole in the arm and the head holding the conductor at a fixed distance from a wall surface.